The field of the invention is closure caps for containers and more particularly is the provision of a novel closure cap which is formed of thin sheet metal and is adapted to be installed onto the top of a beverage bottle of glass or plastic.
Although not limited thereto, the closure cap of the invention is especially intended for use with glass bottles that are used world wide for containing soft drinks and brewed beverages such as beer and ale. The design and dimensions of the open end of such bottle has been fairly standardized and is designated by the standard DIN 6094 in foreign countries, such open end or so-called mouthpiece having a beaded outer rim with an exterior diameter of 26.5 mm. This same standard is universally used in the United States.
The invention has many advantages over the types of closure caps which are in use today and which are known through prior art patents that have not practically been embodied in commercial examples. These advantages will to some extent be brought out by describing some prior art closure caps and explaining their disadvantages.
So far as known there is no commercially available closure cap which is reliably capable of relieving the pressure within a beverage container without blowing off the closure cap. Bottled beverages consist generally of two types, those which are gaseous and those which are still. Both types may be required to pass through autoclaves for pasteurization purposes and thereby are subjected to high pressures produced by the elevated temperatures that are involved. Pasteurization of beer, for example, is effected at a temperature of about 72.degree. C. in which the internal pressure of a container will rise to well over 10 bars (one bar equals 1 megadyne per square centimeter) for a beverage that has about 4 or more grams of carbon dioxide per liter dissolved in the liquid.
At such pressures and higher, which are common in the beverage industry, containers are known to burst. This is especially true in the case of glass bottles which are of the refillable type. Fatigue and weaknesses in used bottles are difficult to detect and the result of breakage is loss of the contents in addition to the inconvenience of removing the broken materials from the machinery.
Closure caps made according to the invention can be made to self-vent for a typical closure cap at pressures as much as 10 bars, the venting having no effect upon the subsequent sealing of the container. The pressure within the container thus drops to as low as 5 bars or so and upon build-up will again vent without adverse effects. Breakage and loss of contents are thereby reduced if not eliminated in pasteurizing beverages. The invention also enables closure caps to be made for self-venting and sealing at pressures which are substantially lower than 10 bars.
In the case of sterilizing which is effected usually for liquids which are not gaseous, the autoclave temperatures are from about 123.degree. C. to 133.degree. C. and are maintained at this temperature for up to 40 minutes. The pressures can and usually do rise to values which can burst containers in such cases and the closure caps of the invention will vent long before the breaking point of the container thereby saving the container and the contents while not interfering with the sterilization process.
Gaseous beverages such as soft drinks and beer are also subjected to high pressures during storage and transportation and even while in the possession of the user. Heat and agitation of the container will increase the internal pressure and can result in explosions of the containers. There are losses of containers and contents in transportation, storage and even in sales outlets where ambient conditions result in high temperatures. As for the explosion of containers in the possession of users, this is most common with used containers but occurs with new containers as well and is a constant source of expense for bottlers who are required to provide insurance and defend against lawsuits for injuries. Even more importantly, there is always a danger to the user of carbonated beverages from injuries which could be sustained through explosion of the container where the internal pressure is excessive or becomes excessive through high temperature or agitation.
Another problem with prior closure caps has been the crazing and chipping caused by the application of the closure cap to the container and such damage caused by the user when opening the same. This is especially true with the so-called crown caps that are crimped in place with multiple dimples or crimps and which require a bottle opener to remove the same. In either case the user will not imbibe in the contents because of the presence of glass chips or evidence on the bottle opening that such chips or shards of glass may have fallen into the bottle.
This disadvantage is eliminated by the invention because the closure caps of the invention can be installed onto containers with substantially less axial pressure than prior closure caps. For example, in the case of crown caps compared to the closure caps of the invention, the axial pressure required for reliably sealing the closure caps of the invention is at least 25% less than required for crown caps. The crown caps which are meant are those which generally have an interior disc-like gasket of cork or similar material within the crown.
There is another disadvantage of prior closure caps of all kinds. This has to do with the opening of the container for use. The contents are under pressure and the degree of pressure is dependent upon the temperature and the amount of agitation to which the container has been subjected. The act of opening the container for all types of closures, not only the crown cap type, is accepted as adventuresome by users--not because of enjoyment but because there is no way of controlling the release of pressure. It can be gradual or explosive, the latter being the most common type of relief. The contents of the containers may be expelled during the opening to varying degrees causing inconvenience and annoyance.
According to one aspect of the invention this disadvantage is alleviated if not completely eliminated by providing for controlled relief of the internal pressure of the container contents during the opening of the container by the closure cap of the invention.
An important advantage of the invention is concerned with the inherent self-valving effect of the closure cap which occurs during the period when the container carrying the closure cap is pasteurized or heated for other purposes at temperatures which are below that required to sterilize the contents. This advantage is that the valving effect enables the discharge of some of the air which may have been included with the contents during filling. If not replaced by the gases in the liquid contents a slight vacuum may obtain above the liquid. In either event the growth of bacteria of the aerobic type is inhibited.
It has been difficult if not totally impractical to apply closure caps of a type which are applied by axial engagement to plastic bottles because of the danger of crushing the bottle or collapsing its neck. The axial pressure used to install the closure cap of the invention is so low that the successful application to plastic bottles is a reality. The need for expensive screwcap types of closures is thus eliminated along with the possibilities that the cap may be removed illegally and other contents substituted in whole or in part. The closure cap of the invention is wholly pilfer-proof because the closure cap is physically and obviously altered in the act of removal.
There are several types of closure caps besides the crown cork crimped or the crown cork twist-off types which are used on bottles and each has its disadvantages. These are variously known as "Alka", "Rip Cap" and "Maxicap". The latter two have parallel rip lines which pass over the top or crown of the closure so that the user must either pull the tab all the way to divide the closure into three pieces or he must manipulate the cap parts to separate them for removal from the bottle in order to gain access to the contents. There is no need to describe the inconvenience and difficulties with such closure caps. Manipulation of the cut-open parts can result in finger injuries.
The type of closure cap which has been referred to as "Alka" is characterized by a pull tab and a weakened rip line that tears away a portion of the wall of the cap leaving the user to manipulate the remainder of the cap from the bottle. On the other hand the closure cap of the invention is simple and effective because it is easily removed by a single circumferential movement that so fully loosens the cap that it is easily picked off by the user. Notwithstanding this, the cap can be replaced onto the bottle and will remain in place whereby the contents may be kept clean for a time. The pressure is not retained after opening but the bottle can be covered by the closure cap sufficient to protect the contents temporarily.
The closure cap of the invention is preferably made out of aluminum or an aluminum alloy. Accordingly it is light in weight and rust-proof. Other thin sheet metals could be used with advantage if properly formed and installed as will be explained hereinafter. Steel would have to be lacquered or otherwise coated to prevent rust; hence the aluminum closure cap is preferred.
In the crown cork type of closure cap the sides of the closure cap are ribbed making it difficult to carry graphic material legibly thereon. The side wall of the closure cap of the invention is smooth with a minimum of wrinkles which provides much space for graphic material in addition to eliminating sharp protruding edges which could cause injuries.
Especially in the case of aluminum closure caps according to the invention, application is rapid and the forces required are less than in the case of the ordinary closure caps made out of steel.
Many other advantages and attributes of the invention will become obvious as a description of the preferred embodiments is set forth hereinafter.